甘肃黑方台黄土水分运动参数试验研究

Experimental Study of Loess Moisture Movement Parameters in Heifangtai of Gansu Province

灌溉渗透诱发型黄土崩滑灾害在黄土高原具有普遍性,其中以黑方台灌区最具典型性和代表性.从非饱和土力学角度看,黄土在灌溉后更易发生蠕变变形和破坏.黄土含水量这个土壤水分运动参数将对黄土自身的变形和破坏产生一定的影响,进而造成黄土崩滑灾害的可能.选取甘肃省临夏回族自治州永靖县盐锅峡镇黑方台原状黄土与扰动黄土作为试验介质,采用Ku-p F非饱和导水率测定系统测定其土壤水分特征曲线,并运用MATLAB软件拟合实测数据.结果表明:原状黄土中的大孔隙对土壤水分特征曲线具有显著的影响;原状黄土被扰动重塑后,失水率变大,持水性能变强;原状黄土特殊的结构性将随着水体的侵入而逐渐丧失;张力计法只适合测定低负压范围的水分特征曲线;采用Van方程参数拟合方法拟合渗透系数存在较大误差.

： The irrigation-infiltration-induced loess collapse disasters in the loess plateau are universal, and the irrigation area of Heifangtai is the most typical and representative. From the perspective of unsaturated soil mechanics, creep deformation and failure in loess are more likely to happen after irrigation. The loess soil water movement parameters such as moisture content will have a certain impact on the deformation and failure of the loess itself, causing the loess collapse hazard. This experiment takes the undisturbed loess and disturbed loess, which is from Heifangtai, Yanguoxia Town, Yongjing County, Linxia Hui Autonomous Prefecture, Gansu Province, as the test medium, the soil water characteristic curves of the test medium are measured with the Ku-pF unsaturated hydraulic conductivity measurement system, and the measured data are fitted with MATLAB software. The results show that： large pores in undisturbed loess have significant influences on its soil water characteristic curve ; the filtration rate and water-holding capacity of disturbed and reshaped loess are both stronger than undisturbed loess; the special structure of undisturbed loess will gradually lose as water invading; the tension meter method is only suitable for the determination in low negative pressure range of the moisture characteristic curve; the Van equation parameter fitting method has a big error on fitting permeability coefficient K.